Patent Application
20100294185
The present invention relates to long-arm stitchers and, more particularly, to a control system for long-arm stitchers and the like.
Conventional long-arm sewing machines are generally used for quilting and/or sewing fabrics that are not easily moved through a sewing machine. As such, a long-arm sewing machine is designed to move with respect to a workpiece that is held stationary on a frame. However, the workpieces generally include two outer layers and a filler material that is sewn between the outer layers. Often, the filler being stitched into the workpiece is uneven, thereby adding to difficulties for a stitch regulator to properly control a velocity of the stitcher with respect to the workpiece. Moreover, the stitch design of the workpiece may include several different stitch types and/or a stitch pattern that is not straight, thereby complicating the ability to control the stitch pattern. Accordingly, the velocity of stitcher movement with respect to the workpiece must be varied during stitching to maintain a proper stitch length or number of stitches per inch of the workpiece.
Typically, a stitch regulator is controlled by optical encoders that monitor the stitch pattern as it is being stitch into the workpiece. However, such encoders must be positioned adjacent the workpiece and may resultantly interfere with the stitching operation. In addition, optical encoders are costly and require a significant amount of assembly time. The assembly also generally includes harnesses and cabling to properly install the optical encoder.
As such, it is desirable to control a stitch regulator utilizing a less costly and more easily assembled system that does not interfere with the stitching process.
In one embodiment, a control system for a stitcher is provided that includes a motor driving the stitcher, and a stitch regulator in communication with and capable of altering a velocity of the motor. A controller is in communication with the stitch regulator; and at least one accelerometer is in communication with the controller to determine an acceleration of the stitcher with respect to a workpiece. A signal representing the acceleration of the stitcher with respect to the workpiece is communicated to the controller; and the operation of the stitch regulator is modified as necessary based on the signal.
In another embodiment, a stitcher is provided that includes a needle to stitch a workpiece, a motor to operate the needle, and a stitch regulator in communication with and capable of controlling a speed of the motor. A controller is in communication with the stitch regulator. The stitcher also includes at least one accelerometer in communication with the controller to determine an acceleration of the stitcher with respect to the workpiece. A signal representing the acceleration of the stitcher with respect to the workpiece is utilized to adjust the operation of the needle as necessary.
In a further embodiment a method of operating a stitcher is provided. The method includes providing a stitch regulator for controlling the operation of the stitcher, and providing an accelerometer in communication with the stitch regulator. An acceleration of the stitcher with respect to a workpiece is measured with the accelerometer, and a signal representing the acceleration of the stitcher is sent to the stitch regulator. The method further includes integrating the signal representing the acceleration of the stitcher to determine a velocity of the stitcher with respect to the workpiece, and controlling the stitch regulator utilizing the velocity of the stitcher with respect to the workpiece.
Although the present invention is described with respect to a long-arm stitcher, one of ordinary skill in the art would recognize that the present invention also has applicability with standard sewing machines and could be used in both a commercial and/or household setting. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
During operation, the needle bar 28 moves up and down thereby moving the needle 30 to form a stitch in the fabric. The needle bar 28 can be adjusted up or down to provide a proper machine timing height. A small hole in the needle plate 34 restricts movement of the thread as the stitch is formed. The hopping foot 32 raises and lowers with the movement of the needle 30 to press and release the fabric as the stitch is formed. The hopping foot 32 is designed to be used with rulers and templates and has a height that can be adjusted for proper stitch formation. A control box 48 is provided to control the operation of the stitcher 10.
The control box 48 includes a stitch regulator 50 that controls a speed of the needle 30. Specifically, the needle speed is controlled to accommodate varying thicknesses of the workpiece and varying stitch types. The speed is further controlled to accommodate a stitch pattern that may not be linear.
The accelerometer 52 is electronically coupled to the stitch regulator 50 and is configured to control the stitch regulator 50 based on the algorithm 100 shown in
At step 106, a signal indicative of the stitcher's acceleration with respect to the workpiece is received from the accelerometer 52. The signal is filtered with a low pass filter and sampling losses are removed therefrom, at step 108, to determine an acceleration of the stitcher 10 in both the x-axis and the y-axis. While the present invention is described with respect to both the x-axis and the y-axis, as will be appreciated by one of ordinary skill in the art, the signal may only be indicative of the stitcher's acceleration in one of the x-axis or the y-axis. At step 110, the acceleration signal is integrated to provide a vector velocity of the stitcher 10 in the x-axis and the y-axis, wherein the vector velocities include both a magnitude and a direction. The vector velocity in the x-axis and the vector velocity in the y-axis are summed, at step 112, to provide a vector sum having both a magnitude and direction indicative of a velocity of the stitcher 10 with respect to the workpiece.
At step 114, it is determined whether a position of the stitcher 10 is also desired. If the position is not desired 116, the velocity of the stitcher 10 is used to determine a correction of the stitch regulator 50, at step 118. The stitcher 10 is then operated, at step 104, to stitch a pattern in the workpiece, wherein the stitch regulator 50 controls the number of stitches per inch based on the velocity correction.
If the position of the stitcher 10 is desired 120, the stitcher velocity is integrated, at step 122, to provide a vector position of the stitcher 10 in the x-axis and the y-axis, wherein the vector positions include both a magnitude and a direction. The vector position in the x-axis and the vector position in the y-axis are summed, at step 124, to provide a vector sum having both a magnitude and direction indicative of a position of the stitcher 10 with respect to the workpiece. The velocity and position of the stitcher 10 is then used to determine a correction of the stitch regulator 50, at step 126. The stitcher 10 is then operated, at step 104, to stitch a pattern in the workpiece, wherein the stitch regulator 50 controls the number of stitches per inch based on the velocity and position corrections.
Accordingly, the present invention provides a means to regulate a speed of stitcher needle 30 utilizing the acceleration and position of the stitcher in the x-axis and/or y-axis. Specifically, by determining the acceleration of the stitcher 10, a velocity and displacement of the stitcher 10 is determined and input into the stitch regulator 50. As such, the needle 30 can be regulated based on a velocity and/or displacement of the stitcher 10 with respect to a workpiece, thereby enabling automatic correction of a stitch pattern.
As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.
